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Glossary of OSA attributes
This Glossary alphabetically lists all attributes used in the OSAv20230621 database(s) held in the OSA. If you would like to have more information about the schema tables please use the OSAv20230621 Schema Browser (other Browser versions).

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

Z
Name	Schema Table	Database	Description	Type	Length	Unit	Default Value	Unified Content Descriptor
z	allwise_sc	WISE	Unit sphere position z value	float	8
zAperMag3	atlasSource	ATLASDR1	Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag
zAperMag3	atlasSource	ATLASDR2	Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag
zAperMag3	atlasSource	ATLASDR3	Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag3	atlasSource	ATLASDR4	Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag3	atlasSource	ATLASDR5	Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag3	atlasSource	ATLASv20131127	Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag
zAperMag3	atlasSource	ATLASv20160425	Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag3	atlasSource	ATLASv20180209	Default point source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag3Err	atlasSource	ATLASDR1	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag3Err	atlasSource	ATLASDR2	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag3Err	atlasSource	ATLASDR3	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag3Err	atlasSource	ATLASDR4	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag3Err	atlasSource	ATLASDR5	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag3Err	atlasSource	ATLASv20131127	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag3Err	atlasSource	ATLASv20160425	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag3Err	atlasSource	ATLASv20180209	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag4	atlasSource	ATLASDR1	Point source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMag4	atlasSource	ATLASDR2	Point source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMag4	atlasSource	ATLASDR3	Point source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag4	atlasSource	ATLASDR4	Point source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag4	atlasSource	ATLASDR5	Point source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag4	atlasSource	ATLASv20131127	Point source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMag4	atlasSource	ATLASv20160425	Point source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag4	atlasSource	ATLASv20180209	Point source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag4Err	atlasSource	ATLASDR1	Error in point/extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag4Err	atlasSource	ATLASDR2	Error in point/extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag4Err	atlasSource	ATLASDR3	Error in point/extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag4Err	atlasSource	ATLASDR4	Error in point/extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag4Err	atlasSource	ATLASDR5	Error in point/extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag4Err	atlasSource	ATLASv20131127	Error in point/extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag4Err	atlasSource	ATLASv20160425	Error in point/extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag4Err	atlasSource	ATLASv20180209	Error in point/extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag6	atlasSource	ATLASDR1	Point source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMag6	atlasSource	ATLASDR2	Point source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMag6	atlasSource	ATLASDR3	Point source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag6	atlasSource	ATLASDR4	Point source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag6	atlasSource	ATLASDR5	Point source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag6	atlasSource	ATLASv20131127	Point source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMag6	atlasSource	ATLASv20160425	Point source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag6	atlasSource	ATLASv20180209	Point source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMag6Err	atlasSource	ATLASDR1	Error in point/extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag6Err	atlasSource	ATLASDR2	Error in point/extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag6Err	atlasSource	ATLASDR3	Error in point/extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag6Err	atlasSource	ATLASDR4	Error in point/extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag6Err	atlasSource	ATLASDR5	Error in point/extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag6Err	atlasSource	ATLASv20131127	Error in point/extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error
zAperMag6Err	atlasSource	ATLASv20160425	Error in point/extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMag6Err	atlasSource	ATLASv20180209	Error in point/extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zAperMagNoAperCorr3	atlasSource	ATLASDR1	Default extended source Z aperture mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr3	atlasSource	ATLASDR2	Default extended source Z aperture mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr3	atlasSource	ATLASDR3	Default extended source Z aperture mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr3	atlasSource	ATLASDR4	Default extended source Z aperture mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr3	atlasSource	ATLASDR5	Default extended source Z aperture mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr3	atlasSource	ATLASv20131127	Default extended source Z aperture mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr3	atlasSource	ATLASv20160425	Default extended source Z aperture mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr3	atlasSource	ATLASv20180209	Default extended source Z aperture mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr4	atlasSource	ATLASDR1	Extended source Z aperture mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr4	atlasSource	ATLASDR2	Extended source Z aperture mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr4	atlasSource	ATLASDR3	Extended source Z aperture mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr4	atlasSource	ATLASDR4	Extended source Z aperture mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr4	atlasSource	ATLASDR5	Extended source Z aperture mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr4	atlasSource	ATLASv20131127	Extended source Z aperture mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr4	atlasSource	ATLASv20160425	Extended source Z aperture mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr4	atlasSource	ATLASv20180209	Extended source Z aperture mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr6	atlasSource	ATLASDR1	Extended source Z aperture mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr6	atlasSource	ATLASDR2	Extended source Z aperture mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr6	atlasSource	ATLASDR3	Extended source Z aperture mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr6	atlasSource	ATLASDR4	Extended source Z aperture mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr6	atlasSource	ATLASDR5	Extended source Z aperture mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr6	atlasSource	ATLASv20131127	Extended source Z aperture mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag
zAperMagNoAperCorr6	atlasSource	ATLASv20160425	Extended source Z aperture mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAperMagNoAperCorr6	atlasSource	ATLASv20180209	Extended source Z aperture mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zAverageConf	atlasSource	ATLASDR1	average confidence in 2 arcsec diameter default aperture (aper3) Z	real	4		-99999999	meta.code
zAverageConf	atlasSource	ATLASDR2	average confidence in 2 arcsec diameter default aperture (aper3) Z	real	4		-99999999	meta.code
zAverageConf	atlasSource	ATLASDR3	average confidence in 2 arcsec diameter default aperture (aper3) Z	real	4		-99999999	stat.likelihood;em.opt.I
zAverageConf	atlasSource	ATLASDR4	average confidence in 2 arcsec diameter default aperture (aper3) Z	real	4		-99999999	stat.likelihood;em.opt.I
zAverageConf	atlasSource	ATLASDR5	average confidence in 2 arcsec diameter default aperture (aper3) Z	real	4		-99999999	stat.likelihood;em.opt.I
zAverageConf	atlasSource	ATLASv20131127	average confidence in 2 arcsec diameter default aperture (aper3) Z	real	4		-99999999	meta.code
zAverageConf	atlasSource	ATLASv20160425	average confidence in 2 arcsec diameter default aperture (aper3) Z	real	4		-99999999	stat.likelihood;em.opt.I
zAverageConf	atlasSource	ATLASv20180209	average confidence in 2 arcsec diameter default aperture (aper3) Z	real	4		-99999999	stat.likelihood;em.opt.I
zClass	atlasSource	ATLASDR1	discrete image classification flag in Z	smallint	2		-9999	src.class
zClass	atlasSource	ATLASDR2	discrete image classification flag in Z	smallint	2		-9999	src.class
zClass	atlasSource	ATLASDR3	discrete image classification flag in Z	smallint	2		-9999	src.class;em.opt.I
zClass	atlasSource	ATLASDR4	discrete image classification flag in Z	smallint	2		-9999	src.class;em.opt.I
zClass	atlasSource	ATLASDR5	discrete image classification flag in Z	smallint	2		-9999	src.class;em.opt.I
zClass	atlasSource	ATLASv20131127	discrete image classification flag in Z	smallint	2		-9999	src.class
zClass	atlasSource	ATLASv20160425	discrete image classification flag in Z	smallint	2		-9999	src.class;em.opt.I
zClass	atlasSource	ATLASv20180209	discrete image classification flag in Z	smallint	2		-9999	src.class;em.opt.I
zClassStat	atlasSource	ATLASDR1	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	stat
zClassStat	atlasSource	ATLASDR2	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	stat
zClassStat	atlasSource	ATLASDR3	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	stat;em.opt.I
zClassStat	atlasSource	ATLASDR4	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	stat;em.opt.I
zClassStat	atlasSource	ATLASDR5	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	stat;em.opt.I
zClassStat	atlasSource	ATLASv20131127	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	stat
zClassStat	atlasSource	ATLASv20160425	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	stat;em.opt.I
zClassStat	atlasSource	ATLASv20180209	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	stat;em.opt.I
zd	twomass_scn	TWOMASS	Scan's distance from the zenith at beginning of scan.	real	4	degrees		stat.fit.residual;pos.az.zd
zd	twomass_sixx2_scn	TWOMASS	beginning zenith distance of scan data	real	4	deg
zEll	atlasSource	ATLASDR1	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	src.ellipticity
zEll	atlasSource	ATLASDR2	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	src.ellipticity
zEll	atlasSource	ATLASDR3	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	src.ellipticity;em.opt.I
zEll	atlasSource	ATLASDR4	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	src.ellipticity;em.opt.I
zEll	atlasSource	ATLASDR5	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	src.ellipticity;em.opt.I
zEll	atlasSource	ATLASv20131127	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	src.ellipticity
zEll	atlasSource	ATLASv20160425	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	src.ellipticity;em.opt.I
zEll	atlasSource	ATLASv20180209	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	src.ellipticity;em.opt.I
zeNum	atlasMergeLog	ATLASDR1	the extension number of this Z frame	tinyint	1			meta.number
zeNum	atlasMergeLog	ATLASDR2	the extension number of this Z frame	tinyint	1			meta.number
zeNum	atlasMergeLog	ATLASDR3	the extension number of this Z frame	tinyint	1			meta.number;em.opt.I
zeNum	atlasMergeLog	ATLASDR4	the extension number of this Z frame	tinyint	1			meta.number;em.opt.I
zeNum	atlasMergeLog	ATLASDR5	the extension number of this Z frame	tinyint	1			meta.id;em.opt.I
zeNum	atlasMergeLog	ATLASv20131127	the extension number of this Z frame	tinyint	1			meta.number
zeNum	atlasMergeLog	ATLASv20160425	the extension number of this Z frame	tinyint	1			meta.number;em.opt.I
zeNum	atlasMergeLog	ATLASv20180209	the extension number of this Z frame	tinyint	1			meta.number;em.opt.I
zeroPoint	ExternalProduct	ATLASDR2	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	ATLASDR3	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	ATLASDR4	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	ATLASDR5	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	ATLASv20131127	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	ATLASv20160425	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	ATLASv20180209	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	VPHASDR3	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	VPHASv20160112	Zeropoint of each product	real	4		-0.9999995e9
zeroPoint	ExternalProduct	VPHASv20170222	Zeropoint of each product	real	4		-0.9999995e9
zErrBits	atlasSource	ATLASDR1	processing warning/error bitwise flags in Z	int	4		-99999999	meta.code
			Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zErrBits	atlasSource	ATLASDR2	processing warning/error bitwise flags in Z	int	4		-99999999	meta.code
			Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zErrBits	atlasSource	ATLASDR3	processing warning/error bitwise flags in Z	int	4		-99999999	meta.code;em.opt.I
			Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zErrBits	atlasSource	ATLASDR4	processing warning/error bitwise flags in Z	int	4		-99999999	meta.code;em.opt.I
			Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zErrBits	atlasSource	ATLASDR5	processing warning/error bitwise flags in Z	int	4		-99999999	meta.code;em.opt.I
			Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zErrBits	atlasSource	ATLASv20131127	processing warning/error bitwise flags in Z	int	4		-99999999	meta.code
			Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zErrBits	atlasSource	ATLASv20160425	processing warning/error bitwise flags in Z	int	4		-99999999	meta.code;em.opt.I
			Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zErrBits	atlasSource	ATLASv20180209	processing warning/error bitwise flags in Z	int	4		-99999999	meta.code;em.opt.I
			Apparently not actually an error bit flag, but a count of the number of zero confidence pixels in the default (2 arcsec diameter) aperture.
zEta	atlasSource	ATLASDR1	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	pos.eq.dec;arith.diff
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zEta	atlasSource	ATLASDR2	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	pos.eq.dec;arith.diff
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zEta	atlasSource	ATLASDR3	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	pos.eq.dec;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zEta	atlasSource	ATLASDR4	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	pos.eq.dec;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zEta	atlasSource	ATLASDR5	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	pos.eq.dec;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zEta	atlasSource	ATLASv20131127	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	pos.eq.dec;arith.diff
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zEta	atlasSource	ATLASv20160425	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	pos.eq.dec;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zEta	atlasSource	ATLASv20180209	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	pos.eq.dec;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zGausig	atlasSource	ATLASDR1	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	src.morph.param
zGausig	atlasSource	ATLASDR2	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	src.morph.param
zGausig	atlasSource	ATLASDR3	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	src.morph.param;em.opt.I
zGausig	atlasSource	ATLASDR4	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	src.morph.param;em.opt.I
zGausig	atlasSource	ATLASDR5	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	src.morph.param;em.opt.I
zGausig	atlasSource	ATLASv20131127	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	src.morph.param
zGausig	atlasSource	ATLASv20160425	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	src.morph.param;em.opt.I
zGausig	atlasSource	ATLASv20180209	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	src.morph.param;em.opt.I
zHlCorSMjRadAs	atlasSource	ATLASDR1	Seeing corrected half-light, semi-major axis in Z band	real	4	arcsec	-0.9999995e9	phys.angSize;src
zHlCorSMjRadAs	atlasSource	ATLASDR2	Seeing corrected half-light, semi-major axis in Z band	real	4	arcsec	-0.9999995e9	phys.angSize;src
zHlCorSMjRadAs	atlasSource	ATLASDR3	Seeing corrected half-light, semi-major axis in Z band	real	4	arcsec	-0.9999995e9	phys.angSize;em.opt.I
zHlCorSMjRadAs	atlasSource	ATLASDR4	Seeing corrected half-light, semi-major axis in Z band	real	4	arcsec	-0.9999995e9	phys.angSize;em.opt.I
zHlCorSMjRadAs	atlasSource	ATLASDR5	Seeing corrected half-light, semi-major axis in Z band	real	4	arcsec	-0.9999995e9	phys.angSize;em.opt.I
zHlCorSMjRadAs	atlasSource	ATLASv20131127	Seeing corrected half-light, semi-major axis in Z band	real	4	arcsec	-0.9999995e9	phys.angSize;src
zHlCorSMjRadAs	atlasSource	ATLASv20160425	Seeing corrected half-light, semi-major axis in Z band	real	4	arcsec	-0.9999995e9	phys.angSize;em.opt.I
zHlCorSMjRadAs	atlasSource	ATLASv20180209	Seeing corrected half-light, semi-major axis in Z band	real	4	arcsec	-0.9999995e9	phys.angSize;em.opt.I
zKronMag	atlasSource	ATLASDR4	Extended source Z mag (Kron)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zKronMag	atlasSource	ATLASDR5	Extended source Z mag (Kron)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zKronMag	atlasSource	ATLASv20180209	Extended source Z mag (Kron)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zKronMagErr	atlasSource	ATLASDR4	Error in extended source Z mag (Kron)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zKronMagErr	atlasSource	ATLASDR5	Error in extended source Z mag (Kron)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zKronMagErr	atlasSource	ATLASv20180209	Error in extended source Z mag (Kron)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zmfID	atlasMergeLog	ATLASDR1	the UID of the relevant Z multiframe	bigint	8			obs.field
zmfID	atlasMergeLog	ATLASDR2	the UID of the relevant Z multiframe	bigint	8			obs.field
zmfID	atlasMergeLog	ATLASDR3	the UID of the relevant Z multiframe	bigint	8			meta.id;obs.field;em.opt.I
zmfID	atlasMergeLog	ATLASDR4	the UID of the relevant Z multiframe	bigint	8			meta.id;obs.field;em.opt.I
zmfID	atlasMergeLog	ATLASDR5	the UID of the relevant Z multiframe	bigint	8			meta.id;obs.field;em.opt.I
zmfID	atlasMergeLog	ATLASv20131127	the UID of the relevant Z multiframe	bigint	8			obs.field
zmfID	atlasMergeLog	ATLASv20160425	the UID of the relevant Z multiframe	bigint	8			meta.id;obs.field;em.opt.I
zmfID	atlasMergeLog	ATLASv20180209	the UID of the relevant Z multiframe	bigint	8			meta.id;obs.field;em.opt.I
zMjd	atlasSource	ATLASDR3	The mean Modified Julian Day of each detection	float	8	day	-0.9999995e9	time.epoch
zMjd	atlasSource	ATLASDR4	The mean Modified Julian Day of each detection	float	8	day	-0.9999995e9	time.epoch;em.opt.I
zMjd	atlasSource	ATLASDR5	The mean Modified Julian Day of each detection	float	8	day	-0.9999995e9	time.epoch;em.opt.I
zMjd	atlasSource	ATLASv20160425	The mean Modified Julian Day of each detection	float	8	day	-0.9999995e9	time.epoch
zMjd	atlasSource	ATLASv20180209	The mean Modified Julian Day of each detection	float	8	day	-0.9999995e9	time.epoch;em.opt.I
zPA	atlasSource	ATLASDR1	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	pos.posAng
zPA	atlasSource	ATLASDR2	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	pos.posAng
zPA	atlasSource	ATLASDR3	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	pos.posAng;em.opt.I
zPA	atlasSource	ATLASDR4	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	pos.posAng;em.opt.I
zPA	atlasSource	ATLASDR5	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	pos.posAng;em.opt.I
zPA	atlasSource	ATLASv20131127	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	pos.posAng
zPA	atlasSource	ATLASv20160425	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	pos.posAng;em.opt.I
zPA	atlasSource	ATLASv20180209	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	pos.posAng;em.opt.I
zPetroMag	atlasSource	ATLASDR1	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	phot.mag
zPetroMag	atlasSource	ATLASDR2	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	phot.mag
zPetroMag	atlasSource	ATLASDR3	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zPetroMag	atlasSource	ATLASDR4	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zPetroMag	atlasSource	ATLASDR5	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zPetroMag	atlasSource	ATLASv20131127	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	phot.mag
zPetroMag	atlasSource	ATLASv20160425	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zPetroMag	atlasSource	ATLASv20180209	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zPetroMagErr	atlasSource	ATLASDR1	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	stat.error
zPetroMagErr	atlasSource	ATLASDR2	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	stat.error
zPetroMagErr	atlasSource	ATLASDR3	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zPetroMagErr	atlasSource	ATLASDR4	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zPetroMagErr	atlasSource	ATLASDR5	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zPetroMagErr	atlasSource	ATLASv20131127	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	stat.error
zPetroMagErr	atlasSource	ATLASv20160425	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zPetroMagErr	atlasSource	ATLASv20180209	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zPhoto	twompzPhotoz	TWOMPZ	Photometric redshift obtained with the ANNz framework {image primary HDU keyword: zphoto}	real	4		-0.9999995e9
zppErrBits	atlasSource	ATLASDR1	additional WFAU post-processing error bits in Z	int	4		0	meta.code
			Post-processing error quality bit flags assigned to detections in the archive curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings: Byte Bit Detection quality issue Threshold or bit mask Applies to Decimal Hexadecimal 0 4 Deblended 16 0x00000010 All VDFS catalogues 0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues 0 7 Low confidence in default aperture 128 0x00000080 All VDFS catalogues 1 12 Lies within detector 16 region of a tile 4096 0x00001000 All catalogues from tiles 2 16 Close to saturated 65536 0x00010000 All VDFS catalogues 2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 VVV only 2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All catalogues 2 23 Lies within the underexposed strip (or "ear") of a tile 8388608 0x00800000 All catalogues from tiles 3 24 Lies within an underexposed region of a tile due to missing detector 16777216 0x01000000 All catalogues from tiles In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all Ks band sources in the VHS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zppErrBits	atlasSource	ATLASDR2	additional WFAU post-processing error bits in Z	int	4		0	meta.code
			Post-processing error quality bit flags assigned to detections in the archive curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings: Byte Bit Detection quality issue Threshold or bit mask Applies to Decimal Hexadecimal 0 4 Deblended 16 0x00000010 All VDFS catalogues 0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues 0 7 Low confidence in default aperture 128 0x00000080 All VDFS catalogues 1 12 Lies within detector 16 region of a tile 4096 0x00001000 All catalogues from tiles 2 16 Close to saturated 65536 0x00010000 All VDFS catalogues 2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 VVV only 2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All catalogues 2 23 Lies within the underexposed strip (or "ear") of a tile 8388608 0x00800000 All catalogues from tiles 3 24 Lies within an underexposed region of a tile due to missing detector 16777216 0x01000000 All catalogues from tiles In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all Ks band sources in the VHS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zppErrBits	atlasSource	ATLASDR3	additional WFAU post-processing error bits in Z	int	4		0	meta.code;em.opt.I
			Post-processing error quality bit flags assigned to detections in the archive curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings: Byte Bit Detection quality issue Threshold or bit mask Applies to Decimal Hexadecimal 0 4 Deblended 16 0x00000010 All VDFS catalogues 0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues 0 7 Low confidence in default aperture 128 0x00000080 All VDFS catalogues 1 12 Lies within detector 16 region of a tile 4096 0x00001000 All catalogues from tiles 2 16 Close to saturated 65536 0x00010000 All VDFS catalogues 2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 VVV only 2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All catalogues 2 23 Lies within the underexposed strip (or "ear") of a tile 8388608 0x00800000 All catalogues from tiles 3 24 Lies within an underexposed region of a tile due to missing detector 16777216 0x01000000 All catalogues from tiles In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all Ks band sources in the VHS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zppErrBits	atlasSource	ATLASDR4	additional WFAU post-processing error bits in Z	int	4		0	meta.code;em.opt.I
			Post-processing error quality bit flags assigned to detections in the archive curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings: Byte Bit Detection quality issue Threshold or bit mask Applies to Decimal Hexadecimal 0 4 Deblended 16 0x00000010 All VDFS catalogues 0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues 0 7 Low confidence in default aperture 128 0x00000080 All VDFS catalogues 1 12 Lies within detector 16 region of a tile 4096 0x00001000 All catalogues from tiles 2 16 Close to saturated 65536 0x00010000 All VDFS catalogues 2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 VVV only 2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All catalogues 2 23 Lies within the underexposed strip (or "ear") of a tile 8388608 0x00800000 All catalogues from tiles 3 24 Lies within an underexposed region of a tile due to missing detector 16777216 0x01000000 All catalogues from tiles In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all Ks band sources in the VHS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zppErrBits	atlasSource	ATLASDR5	additional WFAU post-processing error bits in Z	int	4		0	meta.code;em.opt.I
			Post-processing error quality bit flags assigned to detections in the archive curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings: Byte Bit Detection quality issue Threshold or bit mask Applies to Decimal Hexadecimal 0 4 Deblended 16 0x00000010 All VDFS catalogues 0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues 0 7 Low confidence in default aperture 128 0x00000080 All VDFS catalogues 1 12 Lies within detector 16 region of a tile 4096 0x00001000 All catalogues from tiles 2 16 Close to saturated 65536 0x00010000 All VDFS catalogues 2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 VVV only 2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All catalogues 2 23 Lies within the underexposed strip (or "ear") of a tile 8388608 0x00800000 All catalogues from tiles 3 24 Lies within an underexposed region of a tile due to missing detector 16777216 0x01000000 All catalogues from tiles In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all Ks band sources in the VHS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zppErrBits	atlasSource	ATLASv20131127	additional WFAU post-processing error bits in Z	int	4		0	meta.code
			Post-processing error quality bit flags assigned to detections in the archive curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings: Byte Bit Detection quality issue Threshold or bit mask Applies to Decimal Hexadecimal 0 4 Deblended 16 0x00000010 All VDFS catalogues 0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues 0 7 Low confidence in default aperture 128 0x00000080 All VDFS catalogues 1 12 Lies within detector 16 region of a tile 4096 0x00001000 All catalogues from tiles 2 16 Close to saturated 65536 0x00010000 All VDFS catalogues 2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 VVV only 2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All catalogues 2 23 Lies within the underexposed strip (or "ear") of a tile 8388608 0x00800000 All catalogues from tiles 3 24 Lies within an underexposed region of a tile due to missing detector 16777216 0x01000000 All catalogues from tiles In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all Ks band sources in the VHS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zppErrBits	atlasSource	ATLASv20160425	additional WFAU post-processing error bits in Z	int	4		0	meta.code;em.opt.I
			Post-processing error quality bit flags assigned to detections in the archive curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings: Byte Bit Detection quality issue Threshold or bit mask Applies to Decimal Hexadecimal 0 4 Deblended 16 0x00000010 All VDFS catalogues 0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues 0 7 Low confidence in default aperture 128 0x00000080 All VDFS catalogues 1 12 Lies within detector 16 region of a tile 4096 0x00001000 All catalogues from tiles 2 16 Close to saturated 65536 0x00010000 All VDFS catalogues 2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 VVV only 2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All catalogues 2 23 Lies within the underexposed strip (or "ear") of a tile 8388608 0x00800000 All catalogues from tiles 3 24 Lies within an underexposed region of a tile due to missing detector 16777216 0x01000000 All catalogues from tiles In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all Ks band sources in the VHS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zppErrBits	atlasSource	ATLASv20180209	additional WFAU post-processing error bits in Z	int	4		0	meta.code;em.opt.I
			Post-processing error quality bit flags assigned to detections in the archive curation procedure for survey data. From least to most significant byte in the 4-byte integer attribute byte 0 (bits 0 to 7) corresponds to information on generally innocuous conditions that are nonetheless potentially significant as regards the integrity of that detection; byte 1 (bits 8 to 15) corresponds to warnings; byte 2 (bits 16 to 23) corresponds to important warnings; and finally byte 3 (bits 24 to 31) corresponds to severe warnings: Byte Bit Detection quality issue Threshold or bit mask Applies to Decimal Hexadecimal 0 4 Deblended 16 0x00000010 All VDFS catalogues 0 6 Bad pixel(s) in default aperture 64 0x00000040 All VDFS catalogues 0 7 Low confidence in default aperture 128 0x00000080 All VDFS catalogues 1 12 Lies within detector 16 region of a tile 4096 0x00001000 All catalogues from tiles 2 16 Close to saturated 65536 0x00010000 All VDFS catalogues 2 17 Photometric calibration probably subject to systematic error 131072 0x00020000 VVV only 2 22 Lies within a dither offset of the stacked frame boundary 4194304 0x00400000 All catalogues 2 23 Lies within the underexposed strip (or "ear") of a tile 8388608 0x00800000 All catalogues from tiles 3 24 Lies within an underexposed region of a tile due to missing detector 16777216 0x01000000 All catalogues from tiles In this way, the higher the error quality bit flag value, the more likely it is that the detection is spurious. The decimal threshold (column 4) gives the minimum value of the quality flag for a detection having the given condition (since other bits in the flag may be set also; the corresponding hexadecimal value, where each digit corresponds to 4 bits in the flag, can be easier to compute when writing SQL queries to test for a given condition). For example, to exclude all Ks band sources in the VHS having any error quality condition other than informational ones, include a predicate ... AND kppErrBits ≤ 255. See the SQL Cookbook and other online pages for further information.
zPsfMag	atlasSource	ATLASDR1	Point source profile-fitted Z mag	real	4	mag	-0.9999995e9	phot.mag
zPsfMag	atlasSource	ATLASDR2	Point source profile-fitted Z mag	real	4	mag	-0.9999995e9	phot.mag
zPsfMag	atlasSource	ATLASDR3	Point source profile-fitted Z mag	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zPsfMag	atlasSource	ATLASv20131127	Point source profile-fitted Z mag	real	4	mag	-0.9999995e9	phot.mag
zPsfMag	atlasSource	ATLASv20160425	Point source profile-fitted Z mag	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zPsfMagErr	atlasSource	ATLASDR1	Error in point source profile-fitted Z mag	real	4	mag	-0.9999995e9	stat.error
zPsfMagErr	atlasSource	ATLASDR2	Error in point source profile-fitted Z mag	real	4	mag	-0.9999995e9	stat.error
zPsfMagErr	atlasSource	ATLASDR3	Error in point source profile-fitted Z mag	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zPsfMagErr	atlasSource	ATLASv20131127	Error in point source profile-fitted Z mag	real	4	mag	-0.9999995e9	stat.error
zPsfMagErr	atlasSource	ATLASv20160425	Error in point source profile-fitted Z mag	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zpSystem	ExternalProduct	ATLASDR2	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	ATLASDR3	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	ATLASDR4	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	ATLASDR5	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	ATLASv20131127	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	ATLASv20160425	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	ATLASv20180209	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	VPHASDR3	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	VPHASv20160112	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zpSystem	ExternalProduct	VPHASv20170222	System of zeropoint (Vega/AB)	varchar	16		'NONE'
zSeqNum	atlasSource	ATLASDR1	the running number of the Z detection	int	4		-99999999	meta.id
zSeqNum	atlasSource	ATLASDR2	the running number of the Z detection	int	4		-99999999	meta.id
zSeqNum	atlasSource	ATLASDR3	the running number of the Z detection	int	4		-99999999	meta.number;em.opt.I
zSeqNum	atlasSource	ATLASDR4	the running number of the Z detection	int	4		-99999999	meta.number;em.opt.I
zSeqNum	atlasSource	ATLASDR5	the running number of the Z detection	int	4		-99999999	meta.id;em.opt.I
zSeqNum	atlasSource	ATLASv20131127	the running number of the Z detection	int	4		-99999999	meta.id
zSeqNum	atlasSource	ATLASv20160425	the running number of the Z detection	int	4		-99999999	meta.number;em.opt.I
zSeqNum	atlasSource	ATLASv20180209	the running number of the Z detection	int	4		-99999999	meta.number;em.opt.I
zSerMag2D	atlasSource	ATLASDR1	Extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	phot.mag
zSerMag2D	atlasSource	ATLASDR2	Extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	phot.mag
zSerMag2D	atlasSource	ATLASDR3	Extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zSerMag2D	atlasSource	ATLASv20131127	Extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	phot.mag
zSerMag2D	atlasSource	ATLASv20160425	Extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	phot.mag;em.opt.I
zSerMag2DErr	atlasSource	ATLASDR1	Error in extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	stat.error
zSerMag2DErr	atlasSource	ATLASDR2	Error in extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	stat.error
zSerMag2DErr	atlasSource	ATLASDR3	Error in extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
zSerMag2DErr	atlasSource	ATLASv20131127	Error in extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	stat.error
zSerMag2DErr	atlasSource	ATLASv20160425	Error in extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	stat.error;phot.mag;em.opt.I
ZSOURCE	mgcBrightSpec	MGC	Identifier for best redshift and quality	varchar	10
zSpec	twompzPhotoz	TWOMPZ	Spectroscopic redshift {image primary HDU keyword: zspec}	real	4		-0.9999995e9
zXi	atlasSource	ATLASDR1	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	pos.eq.ra;arith.diff
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zXi	atlasSource	ATLASDR2	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	pos.eq.ra;arith.diff
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zXi	atlasSource	ATLASDR3	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	pos.eq.ra;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zXi	atlasSource	ATLASDR4	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	pos.eq.ra;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zXi	atlasSource	ATLASDR5	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	pos.eq.ra;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zXi	atlasSource	ATLASv20131127	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	pos.eq.ra;arith.diff
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zXi	atlasSource	ATLASv20160425	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	pos.eq.ra;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.
zXi	atlasSource	ATLASv20180209	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	pos.eq.ra;arith.diff;em.opt.I
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 1.0 arcseconds is used. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the VHS, you might wish to insist that the offsets in the selected sample are all below 0.5 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want. NB: the master position is the position of the detection in the shortest passband in the set, rather than the ra/dec of the source as stored in source attributes of the same name. The former is used in the pairing process, while the latter is generally the optimally weighted mean position from an astrometric solution or other combinatorial process of all individual detection positions across the available passbands.